luftvagon wrote:I got it up to 18 AFR at 65mph at about 85 kpa manifold absolute pressure. It is possible that it could go leaner.... at what risk, I wonder.
Uhm, at frying the top of your pistons, see image for example...
Not what I would call healthy by any account!
The thing is that a temp sensor won't really help you here, and here's why.
At full load a classic engine will want to hover around AFR 13.5, maybe 14.0 if you feel
really froggy. This is so that the fuel helps and cools the
piston surface. As you increase the AFR, you are taking away that cooling effect.
Going super lean can cause nasty things like the burnt piston that I linked, marred cylinders, fried valves, etc. You may also hit detonation issues, which means that you need a knock sensor so that you can retard the timing, which robs you of even more power.
So, essentially better fuel economy and the
death of your engine walk a very fine line. As I said, look at doing 13.5, maybe 14.0 and see what that does for ya. If it's marginal, then take it back down to 13.0 with the knowledge that your engine will last longer.